But experts have warned that the contents of the emails, not their source, should be investigated.

The Hawks are investigating the leaking of about 200 000 emails from the Gupta family and their networks to the media, Business Day reported. However, it is not clear exactly what is being investigated.

Hawks spokesperson Brigadier Hangwani Mulaudzi told Business Day that the inquiry was opened last week. But he would not say if it was the leaking of the emails of their contents that was under investigation.

He told Business Day: "Let's give them space to work on the matter without any undue influence."

The Council for the Advancement of the South African Constitution (Casac) wrote to the acting head of the Hawks, Lieutenant General Yolisa Matakata, asking for an update on the investigation, the paper reported.

Casac's Lawson Naidoo told Business Day: "We need the Hawks to act and they should be investigating these things and they should be verifying some of the information that is in the emails, saying, 'well if this is true then this constitutes a criminal offence and therefore we have to take it further'."

City Press reported that four investigations into allegations that the Gupta family moved billions out of the country are being ramped up.

The Hawks' Serious Corruption Investigation Unit are reportedly investigating not only the Guptas but also former Eskom CEO Brian Molefe and President Jacob Zuma's son Duduzane, the paper reported.

Documents obtained by City Press reportedly show that the Hawks have, among other things, already obtained detailed bank statements from Molefe and detailed statements from Gupta-owned companies.

Allegations made by former deputy finance minister Mcebisi Jonas, that the Guptas offered him a R600 million bribe to take up the post of finance minister, have reportedly been forwarded to prosecutors.

Meetings have already been held with Treasury, the Financial Intelligence Centre and the South African Reserve Bank, the paper reported.